Author: Roussel, Jean-Marc

Source: Canadian Journal of Fisheries and Aquatic Sciences, Volume 64, Number 5, May 2007 , pp. 786-792(7)

Publisher: NRC Research Press

Abstract:

Laboratory experiments on brown trout (Salmo trutta) embryos suggest that sublethal stress in the gravel nest such as hypoxia may alter the behaviour and survival of fish during the early juvenile period. Eggs and embryos were incubated at constant temperature (8.2 °C ± 0.6 standard deviation) under nonlethal dissolved oxygen (DO) concentrations (3.0 mg·L^-1; 26% air saturation level) and normoxia (10.3 mg·L^-1 DO; 90% air saturation level). The average survival from fertilization to end of embryonic development was 70% and 85% for hypoxic and normoxic groups, respectively. Hypoxic embryos grew slowly compared with their normoxic counterparts, but similar body sizes were observed when yolk-sac absorption was completed. Fish incubated as hypoxic embryos delayed their emergence from the gravel in experimental channels. In presence of freshwater sculpin (Cottus gobio), their swimming activity was reduced by 20%, on average, and predation was enhanced by 14% compared with normoxic groups. Results support the view that subtle events early in a fish's ontogeny can have carry-over effects on later periods of its life cycle, and this phenomenon may be a significant source of variation in salmonid fitness.

Des expériences en laboratoire sur la truite brune (Salmo trutta) indiquent qu'un stress sublétal, tel qu'une hypoxie, dans les nids de gravier, peut altérer le comportement et affecter la survie des poissons au début de leur période juvénile. Des oeufs et des embryons incubés à température constante (8,2 °C ± 0,6, écart type) à des concentrations non létales d'oxygène dissous (OD 3,0 mg·L^-1, 26 % de saturation avec l'air) et en normoxie (OD 10,3 mg·L^-1, saturation avec l'air) ont des survies moyennes respectives de 70 % (hypoxie) et de 85 % (normoxie), de la fécondation à la fin du développement embryonnaire. Les embryons hypoxiques croissent plus lentement que leurs semblables normoxiques, mais ils atteignent des tailles comparables au moment de la fin de la résorption du sac vitellin. Dans des canaux expérimentaux, les poissons incubés en hypoxie durant l'embryogenèse retardent leur émergence du gravier. En présence de chabots (Cottus gobio), leur activité de nage est réduite en moyenne de 20 % et leur prédation accrue de 14 % par comparaison aux groupes normoxiques. Ces résultats appuient l'idée que des événements de faible importance durant le début de l'ontogénie d'un poisson peuvent avoir des effets à long terme durant les périodes subséquentes du cycle biologique et que ce phénomène peut être une source significative de variation de la fitness chez les salmonidés.[Traduit par la Rédaction]

Document Type: Research article

Publication date: 2007-05-01

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• Published continuously since 1901 (under various titles), this monthly journal is the primary publishing vehicle for the multidisciplinary field of aquatic sciences. It publishes perspectives (syntheses, critiques, and re-evaluations), discussions (comments and replies), articles, and rapid communications, relating to current research on cells, organisms, populations, ecosystems, or processes that affect aquatic systems. The journal seeks to amplify, modify, question, or redirect accumulated knowledge in the field of fisheries and aquatic science. Occasional supplements are dedicated to single topics or to proceedings of international symposia.
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